ATLANTA (AP) — It was a problem decades in the making: raw sewage flowing into Proctor Creek, a tributary of the Chattahoochee River that winds through some of the most impoverished parts of Atlanta.

As often as 80 times a year, rainstorms caused the overburdened sewer systems to overflow downtown.

City leaders and residents alike cheered seven years ago when, under a federal decree, Atlanta officials completed a $112 million project that untangled and rerouted the city's water and sewer lines to stop pollution in the Proctor Creek basin. It was a pivotal moment in righting one of Atlanta's most toxic wrongs.

There's just one problem: They missed some spots. Water quality testing has revealed a small but lingering amount of E. coli bacteria in Proctor Creek.

The finding has sent Department of Watershed Management workers back underground to find the sewer pipes that are still sending human waste to the waterway.

The ongoing problems at Proctor Creek highlight the complexity of fixing Atlanta's notoriously troubled water and sewer infrastructure, a system so neglected that it fell under federal oversight in the 1990s following a lawsuit by the Chattahoochee Riverkeeper.

This time around, the Riverkeeper watchdog group says it's sympathetic to Watershed's predicament.

"In a city like this, where you have 1,500 miles of sewer lines, it's not easy (to find all the pipes)," said Sally Bethea, head of the environmental nonprofit. "Underground, it's like spaghetti."

But some of those who live around Proctor Creek, which begins underground near the Georgia Dome and snakes west through neighborhoods including Vine City, English Avenue and Bankhead, aren't nearly as understanding.

Tony Torrence, an English Avenue resident and president of the Community Improvement Association, an environmental justice neighborhood group, is frustrated by the continued failures. This is just one of many water-related issues in his community as Proctor Creek remains plagued by other contaminants, trash and flooding, he said.

"If you fixed the whole system, why do we still have problems?" said Torrence, who works with the West Atlanta Watershed Alliance on water quality testing in his community. "It leaves us at risk every day. We smell it. We breathe it. We live it."

Fixing the Proctor Creek problem was complex because residents there used to be served by a combined sewer system — a large pipe through which both stormwater and raw sewage flowed to a treatment center. But when it rained, stormwater overwhelmed the system, causing it to overflow sewage into the creek.

Under the federal decree, workers had to separate the stormwater and sewage into two separate pipes — a massive undertaking that required them to comb through thousands of underground connections.

"No one had mapped it. There are no good records," said Watershed Commissioner Jo Ann Macrina, who joined the department in 2011. "Even today we can't tell everyone where every pipe is. ... When houses were built, they connected wherever they wanted."

Engineers located and separated 970 connections when they first tried to fix the problem, she said.

But workers missed an unknown number of sewage pipes that are still carrying waste to Proctor Creek.

The first sign of trouble came when groups including the Chattahoochee River-keeper detected high levels of E. coli in the water. Watershed officials later conducted special tests with the EPA determining the fecal bacteria didn't come from animals, but humans.

Watershed has already located 28 sewage pipes still causing pollution in the Proctor Creek basin. Workers have repaired seven since beginning the search last September. They expect to find more.

"You can look back and say we should have found every single one of them," Macrina said. "As we are obligated to do, we will fix what we can find."

Macrina blames lack of sufficient video technology for not finding the some of the smallest of pipes, some just 4 inches wide. No one's entirely sure how workers missed a larger pipe connecting a school to the sewer system, but Macrina believes it was because work was performed in the summer when use of school toilets was down.

The city has spent $88,000 so far to disconnect some of the missed pipes.

The amount of E. coli in Proctor Creek waters is nowhere near previous levels but remains in violation of water quality standards.

Bethea said while the creek runs to the Chattahoochee, the E. coli problem isn't likely a threat to drinking water pulled from the river 60 miles south of Atlanta. The biggest threat would be to people who come into contact with Proctor Creek's waters. Signs warning people to stay out of the nine-mile creek have been posted for years.

"It will impact the river, but it's most impactful in the community around (the Proctor basin)," Bethea said. "That's where the high levels have been creating a public health threat all these years."

What's less clear, though, is whether the missed pipes pose legal ramifications for the city.

Watershed officials say the failures aren't a black eye on the combined sewer overflow work already completed and signed off by the U.S. Environmental Protection Agency.

"What we certified was substantial completion," said Margaret Tanner, a Watershed deputy commissioner. "It's my firm belief they believed everything was completely done and what we're finding now is (minimal)."

The EPA is aware of the issue, a spokeswoman with the federal agency said in a statement.

The agency has not yet met with Watershed to discuss what implications the failures could have under the federal consent decree.

Atlanta received a 13-year extension in 2012 on its second federal decree, one governing sanitary sewer overflow system upgrades.

City officials pledge to get it right this time with the aid of smaller, better quality cameras and tools.

"We will continue because we want to make sure we don't miss anything," Macrina said. "The technology we had then was different than we have now."

The stakes are even higher as the Proctor Creek watershed is now the subject of a federally backed partnership between the EPA, city and private developers. Last year, the creek was added to the Urban Waters Federal Partnership, a distinction that brings special attention and the potential for federal grants from such agencies as the Federal Emergency Management Agency and the U.S. Department of Housing and Urban Development.

Separately, a private development group known as The Emerald Corridor is poised to revamp the creek in exchange for environmental credits from the U.S. Army Corps of Engineers that it can sell to developers.

The Emerald Corridor is working with the nonprofit Trust for Public Land, a group raising money to build trails around the waterway that will connect Cobb County's PATH system to the Atlanta Beltline.

But for Torrence, talk of development is meaningless if the pollution problem isn't solved, and soon.

"The last three mayors said it would be fixed," Torrence said. "We can't wait."

*We welcome your comments on the stories and issues of the day and seek to provide a forum for the community to voice opinions. All comments are subject to moderator approval before being made visible on the website but are not edited. The use of profanity, obscene and vulgar language, hate speech, and racial slurs is strictly prohibited. Advertisements, promotions, spam, and links to outside websites will also be rejected. Please read our terms of service for full guides